Distributor for hydraulic motors

ABSTRACT

A distributor for hydraulic motors with radially arranged pistons including a rotary member located in a housing in communication with fluid inlet and outlet conduits and having inner passages and sealing means for the fluid.

I Umted States Patent [151 3,696,7 1 0 OrteIIi [451 Oct. 10, 1972 [54] DISTRIBUTOR FOR HYDRAULIC [56] References Cited MOTORS UNITED STATES PATENTS [72] Inventor: Aurelio Ortelli, Bologna, Italy A 3,556,151 1/1971 Masuda ..137/625.2l [7 u Riva Gallon! -p- Bologna, Italy 2,845,941 8/1958 Wagner ..251/283 x Filed: Oct. 2 Mercier [21] Appl. No.: 90,219 Primary Examiner-Alan Cohan Assistant Examiner-Robert J. Miller 30] Foreign Application Priority Data Attorney-Guido Modlano and Albert Josrf Nov. 7, 1969 Italy ..24092 N69 [57] ABSTRACT A distributor for hydraulic motors with radially air 'i 91/ ranged pistons including a rotary member located in a :2 gr 23 625 housing in communication with fluid inlet and outlet conduits and having inner passages and sealing means PATENTEDncr 10 m2 SHEEY 1 BF 3 INVENTOR Aurelio ORTELLI Aaufi- AGENT PATENTEDUBT 10 m2 SHEET 2 BF 3 INVENTOR Aurelio ORTELLI PATENTED 10 I 3.696.710

SHEET 3 [1F 3 INVENTOR Aurelio ORTELLI AGENT DISTRIBUTOR FOR HYDRAULIC MOTORS BACKGROUND OF THE INVENTION The present invention relates to a distributor for hydraulic motors having radially arranged pistons and the like.

As is known some distributors for hydraulic motors having radially arranged pistons comprise a member the driving shaft and rotatably mounted in a box-like frame connected to the delivery and discharge conduits or pipes of the working fluid. The said rotary member is provided with passages capable of communicating with the said delivery and discharge conduits with the openings or lights formed in a flat portion of the motor housing, which portion is in tight contact engagement with the relative surface of the said rotary member. The said openings communicate through suitable passages with the spaces or chambers of the radial pistons, thereby the said rotary member effects the desired distribution by putting the same chambers or spaces in communication either with the supply or the discharge conduit according to a preestablished sequence.

Such distributors of known type have, however, some drawbacks among which that of giving a reduced efficiency in terms of volumes when the motors operate at high pressures of the working fluid, and at a low number of revolutions. The high pressure of the fluid causes in fact deformations even very small (of the order of hundredth of mm.) in the portion of the motors housing, in contact with the said rotary member. Such deformations are sufficient to cause the opening of passages for the pressure fluid with consequent losses towards the outlet zone.

As a result, as stated above, a reduction in the volumetric efficiency is obtained which sometimes can be so slow as to cause the motor to stop.

The mechanical efficiency is also reduced in that the said deformations cause a bulging or bending of the motor housing portion adjacent to the said rotating member, and the sliding points are moved away towards the periphery of the member-itself thus increasing the friction forces between the-mechanic elements.

SUMMARY OF THE INVENTION The main object of the present invention is that of substantially eliminating the above-mentioned drawbacks which are found in the known systems, by conceiving a distributor for hydraulic motors having radially arranged pistons and the like, capable of maintaining the volumetric and mechanical efficiency at high rate, even when the said motors are operated at high pressure and low speed.

Another important object of the invention is that of conceiving a distributor for hydraulic motors having radially arranged pistons which are simple to manufacture, of reliable operation and easy maintenance.

According to the invention there is provided a distributor for hydraulic motors having radially arranged pistons, which comprises a member rotatably mounted in a box-like frame connected to the supplying and discharge conduits for the working fluid which rotating member is provided with inner passages for the said fluid and is keyed on the driving shaft adjacent to a portion of the housing of the said'motor provided with fluid passages communicating with the chambers or spaces of the said pistons, and it is characterized in that it is provided with a substantially plate-like fluid-tight element arranged between the said portion of the housing and the said rotating member and formed with fluid passages communicating with the said openings, around the said apertures or holes in the plate-like element on the face adjacent to the said portion of housing, depressed surfaces of suitable area being formed, which are delimited by respective seals for the buildingup of counterpressures capable of maintaining the said plate-like element close to the said rotary member substantially upon the whole surface thereof.

BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will better appear from the following detailed description of a preferred but not exclusive embodiment of a distributor for hydraulic motors having radially arranged pistons, according to the invention, illustrated by way of indicative not limiting example, reference being made to the accompanying drawings in which:

FIG. 1 is a cross-section view of the distributor according to the invention taken along two passages of the working fluid;

FIG. 2 diagrammatically shows in a reduced scale a distributor according to the invention when applied to a hydraulic motor having radially arranged pistons;

FIG. 3 is a cross-section view taken along lines III III in FIG. 1;

FIG. 4 is a cross-section view taken along lines IV IV in FIG. 1;

FIG. 5 illustrates in an enlarged scale a detail in FIG.

FIG. 6 is a section view showing deformations occurring in a conventional distributor of known type; and

FIG. 7 is a section view similar to that in FIG. 1 according to another modification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the above Figures, the distributor 1 according to the invention consists of a box-like structure or casing 2 acting as a cover, a rotary member 3 mounted in said box-like structure, a ring 12 carrying two concentric gaskets 13, a plate-like element 4 to be secured adjacent to a flat portion 5 of the housing of an hydraulic motor 6 having radially arranged pistons and the like.

The rotary member 3 is driven by the driving shaft 7 and comprises two inner passages 8 and 9 which communicate through the gap existing between the member 3 and the box-like structure 2 with two respective passages 10 and 11 formed in the box-like structure 2 and in communication with the supplying and discharge conduits (not shown). When the passage 10 communicates with the discharge, the passage 11 communicates with the supplying conduit, viceversa when the passage 10 communicates with the supplying conduit, the passage 11 communicates with the discharge conduit thus defining one direction of rotation or the other, respectively.

In order to separate the supplying fluid flow from the discharge one, a sorting or divisional ring 12 is coaxially mounted between the rotary member 3 and the box-like structure 2, such a ring being provided with resilient gaskets or seals 13 capable of urging the same against the member 3. The ring 12 is also secured to the box-like structure or frame 2 by means of a pin 14 which prevents the same from rotating but permits slight movements in the axial direction. The box-like structure 2 and the plate-like element 4 are secured to the housing of the motor 6 by means of screws 15. The element 4 is bored in the central portion thereof for the passage of the shaft 7.

The rotary member 3 is then provided on the face adjacent to the plate-like element 4 with two arcuated slots or grooves 16 and 17 communicating with the passages 8 and 9, respectively. There are also provided arcuated balance slots or grooves 16a and 170 which communicate through inner passages (not shown) with the groove 16 and the groove 17, respectively.

When the pressure fluid flows through the passage or opening 10, pressures are built up in the slots 16 and 16a thus obtaining a balance effect whereby the resultant force is advantageously applied at the axes. Similarly when the pressure fluid flows through the opening 11 pressures are built up in the grooves 17 and 170 with a resultant axial force.

On the other side when pressure fluid flows through the opening 10 a force A is obtained which acts from left to right (with the reference to FIG. 1) on the rotating member 3, while when the pressed fluid flows through the opening 11 causes a force B to act in the same direction upon the member 3. The force A is the resultant of the pressures acting upon the member 3 outside the ring 12, while the force B is the resultant of the pressures acting upon the same member 3 inside the said ring 12. Such a ring is arranged in such a manner so that the forces A and B are equal to one another. The arrangement is such so that the counterpressures acting from right to left and due to the presence of the grooves l6-l6a and 17-l7a are kept at values lower than that of the forces A and B so as to cause the rotary member 3 to contact the plate-like element 4 always. When for example the pressure fluid flow occurs through the opening 10, the counterpressure due to the presence of the grooves 16 and 16a is lower than the force A acting in the reverse direction.

By considering now the case of a hydraulic motor having five radially arranged pistons, the plate-like element 4 will be provided with five holes or bores 18 which will be arranged in alignment with the five conduits 19 provided in the housing of the motor 6 and communicating with the chambers of the pistons.

At the bores 18, the plate-like element 4 has on the face opposite the motor 6 depressed portions or areas 18a delimited by endless grooves, each of which comprises two concentric arcuated lengths 18b and two radial or substantially radial sections 18c. Within such grooves gaskets or seals 20, whose shape can be other than that illustrated consisting of resilient materials, are arranged and adapted to provide a tight seal between the housing of the motor 6 and the plate-like element 4. In these areas 18a where the pressure fluid arrives, counterpressures C are built up (FIG. 5) and act from right to left so as to maintain the plate-like element 4 perfectly adherent to the rotary member 3, as shown in FIG. 6.

Due to reaction the portion of the housing of the motor 6 adjacent to the plate-like element 4 will undergo a deformation towards the right, as generally indicated in FIG. 6 (in the latter Figure the deformations have been shown remarkably exagerated in order to illustrate this phenomenon). With the distributor according to the invention, however, such a deformation has no practical effect, because the resilient seals 20 which constantly adhere to both the plate-like element 4 and the housing of the motor, maintain a constant tight seal thus avoiding leakage. It should be noted that in the distributors of known type, leakage often occurs as indicated in FIG. 6. With reference to this Figure, the rotary member 3 is adherent directly to the housing of the motor according to known arrangements, and the deformation of such a housing prevents the pressure fluid in the groove 16 for example from completely reaching the conduits l9 concerned, but allows the same to flow laterally towards the grooves 17 and 17a, i.e., towards the discharge. In this situation the operation is defective and the volumetric efficiency drops, even remarkably, and sometimes the motor is thereby stopped.

The supply to the chambers or cylinders of the pistons of the hydraulic motor occurs through the said grooves 16 and 17 and the pressure-fluid is fed in at the same time through two or three conduits 19 according to the angular position of the rotary member 3. Even when three pistons are fed at the same time, however, the counterpressures which occur at the areas 18a must not build up a resultant force higher than the force A or B, thereby the said 18a have to be correspondingly dimensioned.

Furthermore the axial dimension of the rotary member 3 must be greater than a determined value, so as to guarantee the stiffness of the same member against the pressures. In this manner the surface of the member 3 will be kept flat or plane and adherent to the plate-like element 4, thus avoiding fluid leakage in the sliding zone.

From the above the operation of the distributor according to the invention should be clear.

The pressure fluid flow, such as that through the opening 10, will cause the motor 6 to rotate in one direction due to the fluid being supplied to the pistons through the conduits 19 in communication with the groove 16. At the same time counterforcs will be built up in the corresponding areas 18a, while the portion of the motor housing adherent to the plate-like element 4 will be deformed without, however, causing fluid leakage, due to the presence of the seals 20.

The most important result thus attained is a perfect contact or adherence between the rotary member 3 and the plate-like element 4, the fluid leakage at the sliding zone being completely eliminated.

In other terms the fluid is prevented from flowing, as shown in FIG. 6 when the operative pressures reach high values, as occurs in the distributors of known type.

The distributors according to the invention thus permits a high volumetric efficiency and this particularly with hydraulic motors at low speed and with high operative pressures.

Relative to the known type the distributor according to the invention has also a higher mechanical efficiency because the sliding between the rotary member 3 and the plate-like element 4 occurs on flat surfaces thus obtaining a substantially uniform distribution of the frictional forces. In the conventional types instead, the friction torque increases as the deformation of the portion of the motor housing in contact with the distributor increases, because the sliding points tend to move towards the periphery of the rotary member 3, as may be understood by observing FIG. 6, and therefore the arm of the frictional force elongates.

A further advantage, of the invention consists in that, while in the known typesan excessive wear or sliding in the portion of the motor housing adjacent to the rotary member makes necessary a longer grinding operation, by making use of the distributor described above the restarting of the operation can be effected after a simple replacement of the plate-like element 4 since the possible damages occur in the latter.

- In the modification shown in FIG. 7 designed to obtain a better distribution of the forces A and B relative to the above-mentioned solution, the ring 12 is replaced by a disc-like plate 21 which at the face thereof adjacent to the frame 2 has a central depression 22 and an annular co-axial depression 23 and is provided with ring seals 24.- At the depression 22 there is provided a hole 25 opening into a depression 26 formed in the rotary member 3,.while at the annular depression 23 there is provided a plurality of holes 27 facing an annular groove 28 formed in the member 3 at the passage 9. The plate21 is also secured to the frame 2 by means of two pins 29 which prevent rotation thereof but allow slight axial movements.

In the frame 2 there are provided inner passages 30 designed to put the zone of the depressions 22 and 26 in communication with the peripheral portions of the member 3.

Whith this arrangement the force A is applied to the central zone and to a peripheral annular portion, while the force B is applied to an intermediate annular zone, as indicated by the arrow in FIG. 7. These surfaces are dimensioned in such a manner so that the forces A and B are substantially equal.

The remaining portions of the distributor are similar to those disclosed above.

The embodiment in FIG. 7 has the advantage of allowing a better distribution of the forces A and B to that of the distribution of the forces acting from the op posite side on the areas 16 and 17.

More particularly the force A besides acting on the periphery, acts also on the central zone of the rotary member 3, so that it can prevent in a more efficient manner possible swelling deformations due to pressures acting on the area 16.

The operation of the distributor illustrated in FIG. 7 is similar to that described above.

The invention thus conceived is susceptible to numerous modifications and changes all of which are included in the scope of invention.

In practice the used materials as well as dimensions could be any, according to the requirements and furthermore all the elements could be substituted with other technically equivalent means.

Iclaim:

l. A distributor for hydraulic motors provided with radial pistons, said distributor comprising a casing coaxially secured to the housing of the hydraulic motor and having inlet and outlet par s for the pressure fluid,

a member rotatably mounted in said casing and provided with inner passageways for said pressure fluid which communicate with the chambers of said pistons through respective conduits, said rotatable member being keyed on the driving shaft of the hydraulic motor, a plate-like element arranged between said rotatable member and a plane portion of said housing and having a plurality of through-holes communicating with said conduits, wherein according to the improvement the distributor further comprises depressed portions each formed around the relative hole of said plate-like element on the face adjacent to said housing and delimited by respective seals, at least a ring element arranged between said casing and said rotatable member and associated to said casing to to freely move axially but prevented from rotating, seal means arranged between said ring element and said casing, said ring element defining concentric areas connected with said inlet and outlet parts respectively, the surface of said areas connected to the inlet part and the surface of the depressed areas surrounding the holes connected with the same inlet part being such that the resultant pressure force urges said rotatable member against said plate-like element.

2. A distributor as claimed in claim 1, wherein said depressed areas are surrounded by a groove for the reception of a seal gasket.

3. A distributor as claimed in claim 1, wherein between said casing and said rotary member a disc is inserted, associated with said casing in such a manner that it is slidable axially and not rotatable, said disc being provided with concentric gasket seals on the side adherent to said casing which define a central, a peripheral and an intermediate annular area, some bores being provided in said disc at said central and intermediate areas, the said intermediate area being in communication with an annular groove formed in the adjacent surface of said rotatable member, which annular groove ridge communicates with a fluid passage provided in said rotary member, other passages being provided to put in communication the central and peripheral areas with one another. 

1. A distributor for hydraulic motors provided with radial pistons, said distributor comprising a casing coaxially secured to the housing of the hydraulic motor and having inlet and outlet parts for the pressure fluid, a member rotatably mounted in said casing and provided with inner passageways for said pressure fluid which communicate with the chambers of said pistons through respective conduits, said rotatable member being keyed on the driving shaft of the hydraulic motor, a plate-like element arranged between said rotatable member and a plane portion of said housing and having a plurality of through-holes communicating with said conduits, wherein according to the improvement the distributor further comprises depressed portions each formed around the relative hole of said plate-like element on the face adjacent to said housing and delimited by respective seals, at least a ring element arranged between said casing and said rotatable member and associated to said casing to to freely move axially but prevented from rotating, seal means arranged between said ring element and said casing, said ring element defining concentric areas connected with said inlet and outlet parts respectively, the surface of said areas connected to the inlet part and the surface of the depressed areas surrounding the holes connected with the same inlet part being such that the resultant pressure force urges said rotatable member against said plate-like element.
 2. A distributor as claimed in claim 1, wherein said depressed areas are surrounded by a groove for the reception of a seal gasket.
 3. A distributor as claimed in claim 1, wherein between said casing and said rotary member a disc is inserted, associated with said casing in such a manner that it is slidable axially and not rotatable, said disc being provided with concentric gasket seals on the side adherent to said casing which define a central, a peripheral and an intermediate annular area, some bores being provided in said disc at said central and intermediate areas, the said intermediate area being in communication with an annular groove formed in the adjacent surface of said rotatable member, which annular groove ridge communicates with a fluid passage provided in said rotary member, other passages being provided to put in communication the central and peripheral areas with one another. 